Telescopic construction



June 29,1965 P. GOLLER TELESGOPIG- CONSTRUCTION 3 Sheets-Sheet 1 Filed May 6, 1963 Fig.7

mmvron PAUL GOLLER flw www June 29, 1965 P. GOLLER 3,191,902

mmsco'rxc cousmnvcnon Filed May a, 1963 3 Sheets-Sheet 2 37 Fig.3

INVENTOR. PAUL 60L LEI? A 7' TORNEVS 11111929, 5 i i P. GOLLER v I 3,191,902

TELESCOPIC CONSTRUCTION Filed May 6. 1963 3 Sheets-Sheet 3 Aid IN VEN TOR. PA 4/4 GOLLflE WZMWW%,

United States Patent 3,191,902 TEIJEEQGPIC CGNSTRUCTIGN Paul Geller, Munich, Germany, assignor to Maschinenfabrik Karl Geller KG, Munich, Germany, a corporation of Germany Filed May 6, 1963, Ser. No. 278,142 Claims priority, application Germany, May 9, 1962, G 34,939 13 flaims. (til. 248-1835) The invention refers to a telescopic guide means, applicable especially as the leg of one-legged, height-adjustable, tables and chairs, said means having at least two tubular members telescopically received into each other and said members being adjustable and fixable as desired with respectto each other by means of a hand-operable eccentric device.

In known telescopic constructions of this kind serving as a table leg, an eccentric device is located'rotatably around a horizontal axis externally of the outer tubular member. In the region of the eccentric the outer tubular member has a slit through which the eccentric can enter into the interior of said tubular member and can engage the inner tubular member. By turning the eccentric means by a handle, the inner tubular member can be pressed tightly against the outer tubular member and can thus be held at any desired relative position.

However, this known telescopic construction has first of all the drawback that the outer tubular member has an opening in the region of the eccentric device which is not completely filled by the eccentric device, so that dirt can enter into the interior of the telescopic construction. This dirt enters between the contacting surfaces and inhibits the easy adjustment of the tubular members. Further, it is very difficult to produce sufficient clamping force with an eccentric which can be turned around an axis perpendicular to the common axis of the telescoped tubular members. The contacting surfaces between the eccentric and the inner tubular member is so small that considerable surface pressure arises between these parts when the inner tubular member is pressed against the inner surface of theouter tubular member with sufiicient force to effect the desired fixing of the one unit with respect to the other. In the case of the known telescopic constructions, the eccentric device may be provided with a concave contour adapted to the curve of the inner tubular member in order to produce a contacting surface that is as large as possible. This makes the fabrication of the eccentric device difiicult and yet it is necessary in order to bring about a linear contact between the eccentric device and the interior tubular member, while avoiding excessive surface pressure therebetween.

The purpose of the present invention is the construction of a telescopic device of'the abov-e-described kind in such a manner that it is protected against the entering of dirt and is furthermore secured by means of an inconspicuous, effective and long-lasting clamping device. The present invention achieves these objects (1) by providing interiorly of the two tubular members a clamping shaft positioned parallel to the common axis of said tubular members, (2) by effecting rotation of said clamping shaft by means of a handle protruding radially at the end of one tubular member to activate an eccentric device which in turn acts upon the inner wall of said one tubular member, and (3) by installing the clamping shaft nonslidably in the other tubular member parallel with the axis of the tubular members. 7

Because of the axial positioning of the clamping shaft in the interior of the two tubular members, no side opening is needed through the tubular member. The telescopic device can, therefore, be completely closed off, so that no dirt can enter between the contacting surfaces.

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Thus, the telescopic device is easily adjusted even after having been in use for a long time.

Since the handle protrudes from the end of one tubular member, it can be attached inconspicu-ously and other operating parts of the clamping device are concealed. This is particularly important in View of the fact that the evice according to the present invention is used in the construction of furniture. Protruding and conspicuous parts of a clamping device would impair the appearance of the furniture piece.

In a preferred embodiment of the invention, there is provided a pressure piece which is movable transversely to the axis of the tubular members and is located between the eccentric device and the inner surface of the tubular member on which it acts. Thus, an eccentric type of clamping effect can be achieved in the case of tubular members of various cross sections. The contour of the pressure piece can easily be adapted to inner tubular member surfaces of any shape. This is further advantageous in that it makes possible a coaxial arrangement of the two tubular members with respect to each other and makes it possible to easily replace a worn pressure piece.

If tubular members of circular cross section are used, it may be desirable to guide the clamping shaft on at least one transverse bridge in one tubular member and to connect it nonrota'tably with an eccentric, which latter has a cylindrical surface lying against the inner Wall of the other tubular member, said last-named member being arranged eccentrically with respect to the clamping shaft. The curved surface of the eccentric device bears against the inner surface of the tubular member over a large area so that a large clamping force can be achieved with little wear.

. Additional characteristics and advantages of the invention are shown in the following description, combined with drawings, of a preferred embodiment.

The drawings show: 7

FIGURE 1 shows a side view, partially in longitudinal section, of a telescopic device constructed as a table leg with an eccentric clamping device according to the invention.

FIGURE 2 shows a section through the telescopic device taken on the line IIII in FIGURE 1.

FIGURE 3 shows a modification of the telescopic device according to the present invention, partially in longitudinal section and partially in side elevation.

FIGURE 4 is a view, on an enlarged scale, of a fragment of FIGURE 1.

FIGURE 5 is a sectional view taken on the line VV of FIGURE 4.

The embodiment of a telescopic device shown in FIG- URES 1-2 of the drawing represents at 1 the leg of a one-legged table or chair. The device consists of a fixed outer tubular member 2 and a longitudinally movable inner tubular member 3 guided therein. Said tubular member 3 supports a bracket 4 for the fastening of a table top or a seat. Tubular member 2 rests at its lower end on feet 5. In the embodiment illustrated, tubular member 2 as well as inner tubular member 3 are square in cross section. To reduce friction, corner cages 6 are arranged in two opposite corners between the tubular members. In these cages balls 7 are provided as friction-reducing bodies. Outer tubular member 2 has no openings whatsoever and is closed at its top by ring disk 2a, so that the operating parts of the telescopic de vice are completely sealed and protected against the entry of dirt from the outside.

In order to fix the tubular members 2 and 3 in the respective positions desired, an eccentric clamping device is provided. This device comprises a clamp shaft 8 p which in the embodiment shown is arranged rotatably in the interior of inner tubular member 3 and is held against sideward movement therein by the guide 9 and support 19. To effect rotation of the clamp shaft 8, the hand lever 11 is provided which protrudes sidewards from the inner tubular member through slot 52. This slot is of sufficient circumferential length to permit the turning of lever 11 to the extent necessary for the activation of the clamping device.

Clamp shaft 8 carries an eccentric generally designated at 12. Between this clamp shaft 8 and the interior space of the outer tubular member 2 (in the construction according to FIGURES 1-2) there is inserted the pressure piece 13, the same being movable transversely to the axis of the tubular members. Thus, the pressure piece 13 is movable radially of the inner tubular member 3 through the opening 14 provided therethrough. To extend the guide surface for said pressure piece, a small plate 15 is welded exteriorly of the inner tubular member 3, said plate being provided with a hole aligned with the opening 14.

It is advantageous to conform the radial outward or head surface 13a of the pressure piece 13 to the inner surface of the outer tubular member 2. In the embodiment shown, where the outer tubular member 2 has a planar inner surface, this means that the pressure piece 13 has a head surface 13a which is also planar. For example, in this case a simple cylindrical peg with a planar end can be used as the pressure piece.

In the illustrated example, the outer tubular member 2 and the inner tubular member 3 are coaxial with respect to each other and the clamp shaft 8 is also coaxial to the tubular members. However, it is necessary that the inner tubular member present an eccentric surface in order to move the pressure piece 13 and accordingly such a surface is formed by providing the guide member 9 with an eccentric groove 16 into which the pressure piece 13 enters. The guide member 9 thus has two functions: on the one hand, it supports clamp shaft 8 against sideward displacement and on the other hand it serves as an eccentric for the tightening of the pressure piece 13. This provides an extremely simple construction for accomplishing these purposes.

In order to effect an automatic movement of the inner tubular member outwardly of the outer tubular member when the clamping device is released, a supporting spring 17 is provided with one end thereof supported on and by the bottom of the outer tubular member 2. Advantageously, the clamping shaft 8 is constructed as a hollow shaft whereby the supporting spring 17 enters into said hollow clamp shaft 8 and is guided by it. In this construction, the guide member 9 is constructed as a ring through which the supporting spring 17 extends, the upper side of said ring being attached in a convenient manner, such as by welding, to the lower end of the clamp shaft 8. The upper end of the spring 17, namely, the end thereof entering into the clamp shaft 8, bears against an insert piece 18 which is solidly connected with the clamp shaft 8. Said insert piece 18 also supports a hand lever 11. This construction results in the supporting spring 17 not only serving to urge the inner tubular member constantly upwardly and in a direction away from the outer tubular member, but it also secures the clamp shaft 8 against axial displacement with respect to the inner tubular member.

The drawing shows the clamping apparatus in a released condition. The pressure piece 13 is shown at the lower end of the eccentric groove 16 and it is held free from pressure although with its head surface in contact with the inner surface of the tubular member 2. By moving the hand lever 11 in a selected circumferential direction, a shallower portion of the eccentric groove 16 comes in register with the pressure piece 13, with the result that the latter is impelled outwardly, namely, toward the right as appearing in FIGURES 1 and 2, whereby to be pressed against the inner surface of the outer tubular member 2. Thus, the inner tubular member 3 can be fixed at any desired height with respect to the outer tubular member 2. When the clamp device is released by opposite movement of the handle 11, the spring 17 urges the inner tubular member 3 upwardly out of the outer tubular member either until the clamping device is again tightened or until the upper front edge of the cage 6 touches the ring piece 2a. Entry of the inner tubular member 3 into the outer tubular member is limited by the bar 19, having a square cross section, which bar reaches from the bottom of the outer tubular member 2 to a point near its upper end.

In FIGURE 3 of the drawing, there is represented at 20 the leg of a one-legged chair with a height-adjustable seat. This leg is again constructed as a telescopic devioe with two tubular members 21 and 22 of circular cross section telescoped into each other. In the embodiment shown, a schematically indicated seat 23 is attached to the upper end of the inner tubular member 21. The outer tubular member 22 is supported upon a foot 24 in a manner described in more detail below. This foot can advantageously consist of three foot supports arranged equiangularly with respect to each other and projecting radially from the chair leg. A sliding ring 25 and a transverse bridge 26, both of circular construction, are fixedly connected to the interior tubular member 21 and both said ring and said bridge lie against the interior wall of the outer tubular member 22. Thus, the circumferential outer surfaces of the ring 25 and the bridge 26 in cooperation with the cooperating inner wall of the outer tubular member 22 form the contact surfaces for the telescopic engagement in this embodiment. By means of a resilient ring 27 at the upper end of the outer tubular member 22, the same being secured against axial displacement, the maximum extension of the telescoping device can be limited.

In order to fix the seat 23 of the chair at a desired height level, there is provided a suitable eccentric clamping device by means of which the two tubular members 21 and 22 can be fixed in any desired position with respect to each other. The clamping device of the invention is here provided with a clamp shaft 28 which is arranged within the interior of the tubular members 21 and 22 and is positioned parallel to the common axis of said tubular members. The clamp shaft can be rotated by means of the handle 29 which protrudes radially from the side of the inner tubular member through a slot 30 located in the upper end of the inner tubular member 21. Firmly connected with the clamp shaft 28 is an eccentric 31 which lies against the inner cylindrical surface of the outer tubular member 22. The clamp shaft 28 is positioned within the inner tubular member 21 in such a manner that it can be rotated but it cannot be moved transverse with respect to the axis of the tubular members.

In the embodiment shown in FIGURE 3, the clamp shaft 28 is shown as a straight rod or pipe and it is arranged eccentrically to the common axis of the tubular members 21 and 22. An eccentricity of approximately 0.5 mm. appears to be desirable. In order to guide the clamp shaft 28 eccentrically within the inner tubular member 21 and also to secure it against sidewise displacement guide openings 33 and 34 are provided, respectively, in a transverse bridge 26 and in a further transverse bridge 32 which latter is located at the upper end of the inner tubular member. These openings are offset transversely from the axis of the tubular member to the extent of the eccentricity of the clamp shaft 28 and said clamp shaft 28 extends through said openings. In this case the eccentric device 31 can be constructed as a simple cylindrical disk which normally is in contact by its circumferential outer surface 31 with the inner wall of the outer tubular member 22. The construction of the clamping device in this form is particularly simple inasmuch as the clamp shaft 18 a straight rod without any eccentric, protrusions, pegs or similar.

Although'it is normally desirable to guide the clamp shaft in the inner tubular member in such a manner that it cannot be moved sidewardly, and also to arrange the eccentric in the outer tubular member since this means that the clamping shaft does not have to be made of excessive length, yet it is entirely feasible to guide the clamp shaft in the outer tubular member without sideward movement and to arrange the eccentric in the inner tubular member.

Advantageously, the transverse bridge 26 may be attached by any convenient means, such as by Welding and the eccentric will be arranged in such a manner that its upper surface is fiat and lies against the transverse bridge 2-6. Thus, when the eccentric is rotated the clamp shaft is not subjected to strain by bending but is required merely to resist shear forces.

The adjustment of the telescopic device according to FIGURE 3 proceeds in the following manner:

When the eccentric 31 and the circular transverse bridge 225 are in substantial registry with each other, then no clamping action occurs and the inner tubular member can move freely relative to the outer tubular member. After the seat 23 has been placed into the desired position, hand lever 29 is actuated to rotate the clamp shaft 28. This effects rotation of the eccentric disk 31 but the interior tubular member 21 with its transverse bridges 26 and 32 does not follow the turning movement inasmuch as the clamp shaft turns within the guide openings 33 and 34. Because of the eccentric relationship between the eccentric disk 31 on clamp shaft 23, rotation of the clamp shaft will effect relative radial movement between the transverse bridge 26 and the eccentric disk 31. This movement, although it is very small because of play existing at the contact surfaces and clearance within the openings 33 and 34, effects a strong frictional engagement between the contacting surfaces or the inner and outer tubular members. The inner tubular member is thus locked into the outer tubular member 22 at a desired height.

The clamping force produced by the eccentric is transmitted on the one hand to the cylindrical circumferential surface 31 of the eccentric 31 and on the other hand to a similarly cylindrical circumferential surface of the transverse bridge 26. Since the clamping force thus takes place on a surface of substantial area, the unit surface pressure remains small.

FIGURE 3 also shows that the eccentric clamping device shown therein, because of the use of an axially arranged clamp shaft 28, does not require any openings in the external tubular member 22 so that the actual telescopic device is completely sealed off and protected against the entry of dirt.

To be able to carry out the height adjustment of the chair seat with as little force as possible, there is provided the pressure spring 35 compensating for the weight of the chair which spring is supported at its lower end on a plate 36 which in turn is connected with a foot 24 through a screw 37. The pressure spring 35 bears at its upper end against the eccentric disk 31. To provide a guide for the spring 35 it is preferable to extend the clamping shaft 28 through the eccentric disk 31 so that its end 28 enters. into the pressure spring 35. If the diameter of the clamp shaft 28 is not sufficient for proper guidance of the spring 35, then a sleeve 38 with an appropritate outer diameter can be telescoped onto the end 2 and suitably connected thereto, such as by welding. A further guide 39 is provided at the lower end of the spring 35 for retaining same in its proper position. This guide is fastened to the plate in any convenient manner,

such as by welding. Thus, in this preferred embodiment,

the eccentric disk 31 not only serves its main function as a clamping device, butalso as a support for the weightcompensating spring.

If the telescoping device according to the present invention is used as the leg of a one-legged chair, the chair leg can be constructed as a resilient and revolving leg. This follows because of the arrangement of eccentric clamping device in the interior of the two tubular members. For this purpose the outer tubular member 22 is introduced into a standing tubular member 40 which is solidly connected through the foot 24 to the plate 36. A slide ring 41 and a slide bridge 42 are attached to the outer tubular member 22. The circumferential surfaces of said slide ring and slide bridge cooperate with the interior surface of the standing tubular member 40 to act as guide surfaces for relative axial movement of the outer tubular member 22 in and with respect to the standing tubular member 4% The outer tubular member 22 is here supported on plate 36 and connected with the foot 24 through the strong pressure spring 43. I A thrust hearing structure 44 is provided between the pressure spring 43 and the sliding bridge 42. As can easily be seen from FIGURE 3 of the drawings, the outer tubular member, when the telescopic apparatus is locked, can be itself telescoped into the standing tubular member against the force of the pressure spring 43 so that a resilient support of the seat is obtained. The pressure spring 43 must have sufiicient capacity to absorb the weight applied to the chair seat 23. The thrust bearing 44 permits a turning of the seat relative to the foot 24.

Although particular embodiments of the invention have been utilized above to illustrate its principles, it will be recognized that other specific embodiments may be devised expressing the invention. For example, the eccentricity of the clamp shaft with respect to the outer tubular member could also be obtained by arranging said clamp shaft axially with respect to the inner tubular member and arranging the latter eccentrically to the outer tubular member. Furthermore, in the case of tubular members with circular cross sections, an eccentric member could be used which would have the form of a noncircular segment. Finally, it would also be possible in the case of embodiments according to FIGURES 1 and 2 to create an eccentricity between the clamping shafts and the outer tubular member which means that the eccentric fastened to the clamping shaft could be constructed as a simple circular disk.

All characteristics shownin the description or the drawings, including their constructional details even when used in othercombinations, can be of inventive importance.

What is claimed is:

:1. A telescopic construction, especially for use as a table or chair leg, comprising: i

a pair of tubular members mounted in telescopic relation with respect to each other;

a clamp shaft inside of said tubular members, the lengthwise axis of said clamp shaft being parallel with the lengthwise axes of said tubular members;

means supporting said clamp shaft for rotation about its lengthwise. axis with respect to one of said tubular members and holding said clamp shaft against lateral movement with respect thereto;

handle means connected to said clamp shaft whereby said clamp shaft can be rotated;

clamping means on said clamp shaft for rotation therewith, said clamping means having a surface which is eccentric with respect to the other of said tubular members for effecting relative radial movement of said members and thereby releasably clamping together said tubular members in response to rotation of said clamp shaft.

2. A telescopic construction according to claim 1, in which a pressure piece is positioned bet-ween the eccentric surface and the inner surface of said other tubular member, said pressure piece being movable transversely with respect to the axis of the tubular members in response to rotation of said clamp shaft into and out of engagement withsaid inner surface.

3. A telescopic construction according to claim 2, in which said pressure piece is constructed as a cylindrical pin which is axially movable in an opening in said one tubular member, said pressure piece being held against circumferential movement with respect to said one tubular memher.

4. A telescopic construction according to claim -1, in which the contact surface of said pressure piece lying against the inner surface of said other tubular member has the same contour as the contour of the inner surface of said other tubularmember.

5. A telescopic construction according to claim 2, in which the clamp shaft and the tubular members are coaxial with respect to each other, a cylindrical guide memher on said clamp shaft by which it is supported against lateral movement in and with respect to said tubular members, said guide member having an eccentric groove in its circumferential surface int-0 which said pressure piece enters.

6. A telescopic construction according to claim 5, in which said clamp shaft is hollow and said guide member is an outwardly projected flange on said clamp shaft, and including a support spring extending lengthwise through said clamp shaft.

'7. A telescopic construction according to claim 6, in which the support spring urges the clamp shaft toward one end of said one tubular member, said handle means protruding through a slot in said one tubular member adjacent said one end thereof.

8. A telescopic construction according to claim 1, in which said tubular members are of circular cross section, at least one transverse bridge within said one tubular member for supporting said clamp shaft, said clamp shaft being connected in nonrotatable relationship with a disk, said disk having a circular circumferential surface lying against the interior wall of the other tubular member, said other tubular member being arranged eccentrically relative to said clamp shaft.

9. A telescopic construction according to claim 8, in which the transverse bridge is positioned within the inner tubular member and the disk is positioned in the outer tubular member.

1.0. A telescopic construction according to claim 1, in which the clamp shaft extends beyond the clamping means and including a spring supported at one end on said clamping means and at the other end on the lower end of the telescopic construction.

11. A telescopic construction according to claim 1, in which the outer tubular member is arranged in heightadjustable relationship within a further upstanding tubular member, a pressure spring extending between the foot of said further upstanding tubular member and a thrust bearing on said outer tubular members in such a manner that the lengthwise movement of the two tubular members is absorbed resiliently by the pressure spring and the two tubular members can .be rotated in the further upstanding tubular member.

12. A telescopic construction, especially for use as a table or chair leg, comprising:

an upstanding outer tubular member;

an upstanding inner tubular member slidably mounted in telescopic relation in said outer member and extending upwardly therefrom, said members being capable of limited radial movement with respect to each other;

a clamp shaft inside of said inner member and extending from adjacent the upper end thereof toward the lower end thereof;

means within said inner member supporting said clamp shaft for rotation with respect to said inner member and holding said clamp shaft against lateral movement with respect to said inner member;

said clamp shaft having a surface which is eccentric with respect to the inner surface of said outer membet and which is located therewithin;

a pressure piece extending between said eccentric surface and said inner surface through an opening in said inner member where-by rotation of said clamp shaft causes said pressure piece to move into locking engagement with said inner surface whereby said members are moved radially with respect to each other into clamping engagement; and

a handle secured to said clamp shaft adjacent the upper end thereof and projecting through a slot in said inner member whereby said clamp shaft can be rotated with respect to said inner member.

13. A telescopic construction, especially for use as a table or chair leg, comprising:

an upstanding outer tubular member having a circular central opening;

an upstanding inner tubular member slidably mounted in telescopic coaxial relation in said outer member and extending upwardly therefrom, said members being capable of limited relative radial movement with respect to each other;

a clamp shaft inside of said inner member and extending from adjacent the upper end thereof toward the lower end thereof, the axis of said clamp shaft being parallel with and laterally offset from the common axis of said members;

support means within said inner member supporting said clamp shaft for rotation with respect to said inner member;

a disk mounted on said clamp shaft and having a cylindrical peripheral surface contacting the inner wall of said outer member whereby rotation of said clamp shaft moves said inner and outer members radially with respect to each other; and

a handle secured to said clamp shaft adjacent the upper end thereof whereby said clamp shaft can be rotated with respect to said inner member. I

References Cited by the Examiner UNITED STATES PATENTS 2,516,801 7/50 Renaud 248-401 FOREIGN PATENTS 535,710 1/22 France. 40,469 3/22 France.

(Addition to No. 656,640) 41,661 12/32 France.

(2nd addition to No. 656,640) 1,040,113 5/53 France.

68,604 1/58 France (1st addition to No. 1,104,061)

CLAUDE A, LE ROY, Primary Examiner. 

1. A TELESCOPIC CONSTRUCTION, ESPECIALLY FOR USE AS A TABLE OR CHAIR LEG, COMPRISING: A PAIR OF TUBULAR MEMBERS MOUNTED IN TELESCOPIC RELATION WITH RESPECT TO EACH OTHER; A CLAMP SHAFT INSIDE OF SAID TUBULAR MEMBERS, THE LENGTHWISE AXIS OF SAID CLAMP SHAFT BEING PARALLEL WITH THE LENGTHWISE AXES OF SAID TUBULAR MEMBERS; MEANS SUPPORTING SAID CLAMP SHAFT FOR ROTATION ABOUT ITS LENGTHWISE AXIS WITH RESPECT TO ONE OF SAID TUBULAR MEMBERS AND HOLDING SAID CLAMP AGAINST LATERAL MOVEMENT WITH RESPECT THERETO; HANDLE MEANS CONNECTED TO SAID CLAMP SHAFT WHEREBY SAID CLAMP SHAFT CAN BE ROTATED; CLAMPING MEANS ON SAID CLAMP SHAFT FOR ROTATION THEREWITH, SAID CLAMPING MEANS HAVING A SURFACE WHICH IS ECCENTRIC WITH RESPECT TO THE OTHER OF SAID TUBULAR MEMBERS FOR EFFECTING RELATIVE RADIAL MOVEMENT OF SAID MEMBERS AND THEREBY RELEASABLY CLAMPING TOGETHER SAID TUBULAR MEMBERS IN RESPONSE TO ROTATION OF SAID CLAMP SHAFT. 